Electrohydrodynamic atomization, often called electrospray (ES), has recently attracted great attention for potential and practical particle applications in fine powder production, food processing, medicine, pharmaceutics, biology, and chemistry. The technique enables the production of un-agglomerated, monodisperse particles of various materials with sizes ranging from micro-meter to nano-meter. In known ES systems, a liquid meniscus at the exit of a capillary nozzle is subjected to an electrical stress, resulting from a divergent electrical field established between a spray head and a reference electrode. Due to the geometry of capillary nozzles, however, known ES systems have low mass throughput, which makes the feasibility of large scale implementation difficult.
Several recent electrohydrodynamic atomization techniques reportedly increase the mass throughput. For example, in a single-capillary ES nozzle, a multi jet mode can be generated when the applied voltage exceeds a voltage range for a cone-jet mode. However, multiple liquid jets initiated from a single-capillary head are unstable. Arranging a number of individual capillaries in a one-dimensional linear array also increases the total spray liquid flowrate. However, although the one-dimensional arrangement of individual capillaries is easy to construct for laboratory investigation, it is not practical for industrial scale applications. Further each individual capillary uses a separate feeding and/or distribution channel.